This invention is related to the field of telecommunications, and more particularly to a method and system for routing telephone calls between a public switched telephone network and an Internet protocol network.
Communication networks are used extensively in today""s society. There are many different types of communication networks, such as The Public Switched Telephone Network (PSTN), the Internet, and wireless networks. One problem faced today is communication between various types of networks. One of the reasons this communication can be difficult is because of the control language, or protocol, used by each to route messages. This problem may be particularly acute in transmission of telephone calls.
The Public Switched Telephone Network is generally a worldwide voice telephone network accessible to users with telephones and with access privileges. In the United States, this was formerly referred to as the Bell System Network or the ATT Long Distance Network. The command and control language of the Public Switched Telephone Network is built around a connection-oriented class structure. Call processing, the supervision and addressing of a call, is completed by a complex array of switches, processors and control networks.
Currently, the Public Switched Telephone Network uses a signaling system called Signaling System 7 (SS7). The SS7 protocol consists of four basis sub-protocols: a message transfer part, which provides the functioning for basic routing of signaling messages between signaling points; Signaling Connection Control Part (SCCP), which provides additional routing and management functions for transfer of messages other than call set-up between signaling points; Integrated Services Digital Network User Part (ISUP), which provides transfer of call set-up signaling information between signaling points; and Transaction Capabilities Application Part (TCAP), which provides for transfer of non-circuit related information between signaling points. This system has a class structure of specialized devices that perform single-purpose functions. A Class 5 Switch provides local access and call waiting; a Class 4 Switch provides long distance, 1-800-access and billing, for example. Connectivity is connection-oriented, i.e., two devices must establish a discrete, deterministic connection or voice channel before communication can begin, and this connection must remain in place for the duration of the call.
In contrast to the Public Switched Telephone Network, an Internet Protocol network, such as the Internet, use a different control language. This control language is the Internet Protocol (IP), which is a packet-based architecture. Packet networks are generally more economical than circuit switched networks (such as SS7). In an IP network, every packet of information carries all the necessary control information needed to connect the originating device to its destination using only the resources needed. This allows for uncomplicated (less) throttle points, geographic expansion, and transport integration.
An H.323 protocol environment or Session Initiation Protocol (SIP) provides a way for transmitting voice communications within IP networks. In general, H.323 define a set of call control, channel set-up, and code C specifications for transmitting real-time voice and video over networks that do not offer guaranteed service or quality of servicexe2x80x94such as packet networks, and in particular, the Internet, local area networks, wide area networks, and Intranets. SIP is a session-layered control (signaling) protocol for creating, modifying and terminating sessions with one or more participants.
Communication of telephone calls between the Public Switched Telephone Network (which uses SS7 protocol) and IP networks (which additionally use H.323 protocol to transfer voice over the Internet protocol) have traditionally used complicated signaling gateways to perform conversions between the Public Switched Telephone Network signaling functions and the Internet Protocol Network signaling functions. One function that is performed in facilitating communication between various types of networks is determining through which route a telephone call will take place in the network in which the call will terminate. The route a telephone call takes place is comprised of a plurality of trunks. A trunk is a communication line between two switching systems, such as between a central office and a private branch exchange (PBX).
One problem with routing a telephone call, whether between networks of the same type or between different networks, is that complex signaling algorithms are utilized. These algorithms make modifying services to a customer or group of customers cumbersome.
Therefore, a need has arisen for an improved method and system for routing telephone calls. The present invention provides a system and method for routing a telephone call.
According to one embodiment of the invention, a method for routing a telephone call originating at a first network that utilizes a first signaling protocol to termination in a second network that uses a second signaling protocol includes receiving a service request associated with a calling party from the first network and translating the service request. The method also includes determining a route for processing the service request over the second network and generating signaling specifying the determined route. Determining the route for processing the request over the second network includes determining an address for the calling party and accessing a table associated with the address. The table includes a plurality of pointers to a plurality of additional tables. Determining the route also includes accessing at least one of the additional tables specified by at least one of the pointers, and, in response to accessing the at least one of the additional tables, determining the route for processing the request based on the at least one of the additional tables.
According to another embodiment of the invention, a method. A method for routing a telephone call originating at a first network that utilizes a first signaling protocol to termination in a second network that uses a second signaling protocol includes receiving a service request from the first network. The service request is destined for a called party within the second network. The method also includes translating the service request and determining a route for processing the service request over the second network. The method further includes generating signaling specifying the determined route. Determining the route for processing the request over the second network includes determining an address for the called party and accessing a table associated with the address. The table includes a plurality of pointers to a plurality of additional tables. The method also includes accessing at least one of the additional tables specified by at least one of the pointers, and, in response to accessing the at least one of the additional tables, determining the route for processing the request based on the at least one of the additional tables.
Embodiments of the invention provide numerous technical advantages. For example, routing telephone calls between various types of networks allows service providers to combine or unify legacies, circuit-switched networks, and new IP-based solutions where it makes the most sense. Service providers do not need to displace networks in order to develop next generation enhanced services. Instead, they benefit from the best of both worlds (circuit switched and IP-based networks), protecting their existing investment while reducing dependency on proprietary architectures.
Furthermore, embodiments of the invention enable technology vendors to interoperate with other elements in media-controlled or service layers, without having to maintain currency with other vendors"" technology. Embodiments of the invention also allow call routing to be effected through a plurality of nested tables, which are easily modifiable to modify a customer""s services. For example, allowing a particular person to place a 1-900 call is simply effected by changing an entry in a table. Furthermore, the invention allows scalability and flexibility by allowing a subscriber to add tables as needed and add to the tables as needed. Therefore, very complex sets of services and privileges may be easily provisioned not only for a group of subscribers but also can be easily provisioned for a single subscriber.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions and claims.